Perception
by ifonlynotnever
Summary: ONE SHOT. ADD!Sherlock. He doesn't tell anyone when he figures it out, because he knows the way people think.


**Disclaimer:** I claim no ownership of _Sherlock_ or its characters.**  
>CharactersPairings:** Sherlock Holmes, John Watson.**  
>Genre:<strong> Introspective, angst(ish), friendship, psychological.**  
>Rating:<strong> T (mental health issues, mentions of drug abuse).**  
>Word Count:<strong> 1338**  
>Notes:<strong> Another fill for the BBC Sherlock Kink Meme. Prompt: Sherlock has Adult Attention Deficit Disorder. Posted on LJ and AO3.

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><p>He doesn't tell anyone when he figures it out, because he knows the way people think. Because he would rather be thought of as eccentric, as manic, as some kind of scatterbrained genius, than have to deal with the stigma and the misunderstanding and the misconceptions and the idiocy and the disbelief attached to this particular self-diagnosis.<p>

And no one really gives a damn how he thinks, anyway, just that he does. Just that he solves unsolvable problems.

(And he thinks it's perhaps ironic, because it's the deficit that makes him see, that allows him to make those illogically logical leaps from A to B to Z.)

So he keeps the knowledge close to his heart, pressed inside his chest, against the inside of his skull, for eight years. And he tells no one.

No one until John, and even then he tells himself he won't, right up until the moment he does.

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><p>It is a Wednesday when John asks. Wednesday and miserably rainy—the kind of day Sherlock would despise if they hadn't just solved a triple murder meant to look like a pair of suicides. He is mid-explanation when he catches the odd look on John's face.<p>

"What?" he asks, cutting himself off. "You're looking at me funny. What's the matter?"

"What?" John repeats. "No, I wasn't. It's nothing. Keep going."

"You were," Sherlock insists. "What? I'm not wrong, you know. The evidence is all there, if one simply looks."

"I know it is. I just... Sometimes—" John frowns, and Sherlock can _see_ him trying to find the right words. He waits for what feels like a terribly long moment.

"Sometimes," John continues, slowly, "I wonder what it's like. Inside your head. How you think. Is it all... straight? Or—? I mean, does it go... Is it the same? How do you—I don't know. I don't know what I'm trying to say. Do you? No, of course you don't. Sorry, forget it. Forget what I said. So about those tracks in the mud...?"

But now it's Sherlock's turn to frown, because he _does_ know what John's trying to say. He knows it exactly. And part of him, the part of him that keeps his secrets and cares about perceptions, tells him to pick up his explanation where he left off, to delete John's questions, to shut up, shut up, _shut up before you say something he'll misunderstand, he won't get it, he may be a doctor, but that doesn't mean he'll—_

"I have Adult Attention Deficit Disorder," he blurts out instead. "The tracks were deep and well-defined, but—"

"_What?_ Wait, hold—Shut up about the tracks, will you? Attention—ADD? You have ADD?" John looks bewildered. "And you're only telling me this _now_?"

"Why would I tell you at all?" he snaps back. He can feel himself tensing, bracing for the inevitable, for the questions and the judgment, and the probable loss of respect—oh, that will hurt the most, because of all the people in the world, John is the one he least wants to treat him like—like some irresponsible child incapable of sitting still for more than a moment at a time, and he wants to scream, wants to say _That's not it, I know what you're thinking, I can see it and it's not __that__, that's not me, that's not what it's like, I can't control it but that doesn't mean I'm not in control._

John must see the tension because he cuts off whatever he is about to say and cants his head to the side thoughtfully.

"This really bothers you, doesn't it?" he asks softly. "Really. Nothing bothers you, usually, but this does."

Sherlock says nothing, and that is answer enough.

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><p>They don't speak much for the rest of the day. He catches John looking at him from the corner of his eye, but the doctor does not push, so Sherlock pretends not to notice.<p>

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><p>It is three in the morning when the words come, but he knows that if he waits until a reasonable hour, he'll forget them or delete them or think better of them, so he takes the stairs to John's upstairs bedroom two at a time. He nearly hesitates when he gets to the door, but he's gotten this far, so he puts his hand on the doorknob and twists it open.<p>

John is awake before he's halfway across the room, his army-cultivated habits in full force as he snaps upright, his hand scrabbling for a gun that is not beneath his pillow.

"Wh—_Sherlock?_ What are you—What time is it?"

"Late," the detective replies, and plops himself down, cross-legged, on the end of John's bed. "Or early. I don't hate it, you know."

"What? This is important, right? You're not just—"

"The—deficit. Disorder." (And he has John's attention; it is there in the catch of his breath.) "The way I think. I don't hate it. That's not what bothers me."

In the dark, without the distraction of clear vision, Sherlock can just about hear every single one of John's thoughts in his breathing.

"It's not that I can't pay attention. That's not what it is. People think it's that, but it's not. There are things I can concentrate on, and things I can't, depending on what _matters_, and mostly nothing that matters to other people matters to me. I can't concentrate on what I don't care about. Like tunnel vision. The important bits are in the light, but everything else is blacked out. Impossible to see. And time. Time is odd. I lose track. More than most people. Most people have more time, I used to think. Only they don't, do they? They just use it better.

"And inside my head—I don't know. I don't know how it _should_ be, so I don't know how it's different. What _is_ it like inside your heads? You normal people, I mean. I've always wondered. Is it small? Is it linear? Thinking shouldn't be linear. It's nearly as inefficient as thinking circularly." He falls silent, picks at the bedspread beneath his fingers, and waits for the man across from him to say something.

"I see," John murmurs, and it sounds as if he really does, at least a little. Sheets rustle as he sits up a bit straighter, leans forward just the barest inch; he's thought of something. "The cocaine. It...?"

Sherlock peers at John in the dark, feeling a sharp, flighty stab of pride, of approval.

"Mmhm," he hums. "Very good. Central nervous system stimulant, similar in effect to methylphenidate. Shorter in duration, but much stronger. It helped, mostly. Good for thinking, bad for health. Like smoking. That helped, too. In a different way. I miss it. Both its." He has gradually slumped forward, and now leans so far down his head touches the sheets. When he speaks, his voice is muffled. "You were the first one to ask, you know. What it's like. Inside my head. No one else did."

For a long while, there is nothing. Just his breathing, and John's, and the wistful words hanging in the air between them.

And then John sighs, and reaches forward, his touch light but warm against Sherlock's head, fingertips imparting some strange, fleeting comfort that goes right to Sherlock's brain, to his gut, to his heart.

"You're an idiot," John says, but they have known one another for long enough that it means more than that. It means, _You're still who you were._ It means, _I don't think any differently of you._ It means, _You are an idiot, and that's fine, because I am, too. You're fine. It's all fine._

And it drains the energy out of him, leaves Sherlock relieved and exhausted enough that when his flatmate's fingers retreat and he says, "Go to sleep," he does.

Sherlock falls asleep at the foot of John's bed and dreams of wallpapering the inside of his brain, of fixing it up, of making it feel like home.

And it's fine.

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><p><strong>End Notes:<strong> Methylphenidate is the chemical name for such well-known ADD medications as Ritalin and Concerta. Structurally, it's similar to amphetamines, but, as Sherlock says, its effects are more like a weaker, longer-lasting cocaine.

And no, this didn't come out of nowhere. _Tzigane_ was based on the same concept (ADD!Sherlock), though, at the time, I didn't want to label it as such. As for the symptoms Sherlock describes: those are based on my own experiences and, if anything, I hope it dispels (at least a little bit!) the notion that ADD presents as a lifelong sugar rush. It doesn't.

Thanks for reading!


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